1. Field of the Invention
This invention relates to a method for making bone particles useful in a variety of orthopedic applications and to a workpiece forming and holding device for use with the method.
2. Description of Related Art
The manufacture of bone particles, implants containing such particles, and the use of the particles and implants in the repair of bone defects and for other orthopedic applications are known.
The microstructure of cortical bone consists of bundles, or fibers, of mineralized collagen that are oriented parallel to the long axis of the bone. Known methods for making bone particles involve subdividing sections of whole, i.e., mineralized, bone, e.g., by such mechanical operations as shredding, milling, shaving, machining, etc. If desired, the particles can be partially or substantially completely demineralized, e.g., by treatment with acid. The resulting demineralized bone particles exhibit osteoinductive properties that make them useful as, or in, implants intended for use in bone repair and other orthopedic applications.
Because of the mechanical limitations of known and conventional bone milling machinery, e.g., the need to grip the bone stock in the jaws of the machine, only donor bone of fairly substantial size, e.g., intact cortical shafts, can be used as a source for the bone particles. The amount of bone particles that can be produced is limited to some extent by the need to use such relatively large sections of bone. This is a considerable drawback due to the limited availability of donor bone. At this time, regulations do not permit the pooling of donor bone material. Since the quantity of bone particles that can be obtained is limited both by the availability of donor bone and the size of the bone, there is a need for a method of making bone particles that is not subject to the constraints imposed by these limiting factors.